That's not a dumb question, we all have to learn sometime.
jelly rolls are 2 1/2 in strips that are the width of fabric (WOF) or 42 to 44 inches
fat quarters are pieces of fabric cut 18" x 22"
I believe charms are either a 4" square of a 5" square
there are also layer cakes, they are larger squares, but I'm not sure the size, maybe 10"???
and there is another one that is strips like the jelly rolls, I think they are called Honey Buns and are 1 1/2" by WOF.
Hope this helps!